No abstract

In this article, a pentaband rectangular DRA is explored and presented. The proposed antenna has a crescent-shaped radiating element with defected ground structure and it is feed by 50‐Ω microstrip line. The RDRA invariably has two similar dielectric resonators made up of RT5870 is positioned on top of the crescent-shaped patch. With the use of a dielectric resonator, the proposed structure has good improvement in impedance bandwidth and gain. The proposed rectangular DRA has penta operating frequency bands with resonant frequency at 1.49 GHz, 2.00 GHz, 2.50 GHz, 5.49 GHz, and 7.75 GHz. The projected structure exhibits the broadside radiation pattern with the maximum gain and directivity of 4 dBi and 4.5 dBi, respectively. The gig of the projected RDRA is validated with the help of simulated results by CST software. The observed results of the proposed antenna indicate that it can be a potential candidate for GPS, PCS, UMTS, ISM, WLAN, Wi-MAX applications.

The limitation of global bandwidth has inspired the exploration as well as study of wireless access technology called massive MIMO. It is one of the primary technologies for the future networks that cluster the antennas together at the receiver and transmitter for offering high Energy Efficiency (EE) and Spectral Efficiency (SE) with the help of simple processing. Attaining a clear concept regarding the massive MIMO system for handling the primary conflicts is important for the better deployment of 5G to 6G networks. The main intention of this paper is to make a detailed review on SE and EE maximization for massive MIMO systems to transform from 5G to 6G networks. This review plans for studying a set of research contributions for past 10 years. The comprehensive analysis on the “key enabling technologies required for 5G and 6G networks, highlighting the massive MIMO systems” is also presented here. It also explains the fundamental challenges associated with the “channel estimation, precoding, pilot contamination, user scheduling, signal detection, and EE” in a massive MIMO system. Finally, the critical open research conflicts that show the future research in massive MIMO systems for 5G to 6G networks are also be expedited.